Motor learning is a set of processes that leads to a long-lasting adaptive change in an individual's capability to perform a movement. One brain structure necessary for motor learning is the cerebellum, however there are two competing theories regarding its role in learning. One theory contends the cerebellum is the site of learning and memory storage, whereas another argues that the cerebellum computes an instructive signal to mediate learning events outside the cerebellum. This long-standing debate can be resolved by examining what neural signals are available in the cerebellum to induce motor learning in an awake, behaving animal. If the cerebellum computes an instructive signal, then patterns of neural activity in the output neurons of the cerebellum (Purkinje cells) should be correlated to the learned changes. Likewise, if the cerebellum is the site of learning, one set of cerebellar input neurons (climbing fibers) should contain the necessary information to guide learning. Therefore, we propose recording Purkinje cells and climbing fibers during a motor learning task, adaptation of the vestibulo-ocular reflex. We will then ask does the direction of learning best correlate with the direction and amplitude of Purkinje cell or climbing fiber responses?